The NHS is turning a blind eye to the suffering of more than 500,000 people with dementia in England, a cross-party committee of MPs warns in a report today.

The public accounts committee accuses the Department of Health of giving the progressive and terminal brain disease a low priority, leaving relatives to cope as best they can with its devastating consequences.

These informal carers save the taxpayer £5bn a year by looking after dementia sufferers at home, but many feel "abandoned" after diagnosis, with less than 50% receiving the assessment of their needs to which they are entitled, the MPs found. "Parallels can be drawn between attitudes towards dementia now and cancer in the 1950s, when there were few treatments and patients were commonly not told the diagnosis for fear of distress."

When diagnoses were made, they were often communicated insensitively and the task of coordinating care from different parts of the NHS and social services was usually left to carers.

The committee called for the NHS to give dementia the same high priority as cancer and heart disease and urged the Department of Health to appoint a dementia tsar to drive through improvements in diagnosis, treatment and care.

It said the condition caused 3% of deaths in 2005 and may have contributed to 13%. It cost the health and social care economy in England £14.3bn a year - more than cancer, heart disease and stroke combined. The number of sufferers was expected to rise from 560,000 to 1 million by 2031 and 1.4m by 2051.

The MPs said Britain ranked in the bottom third of European healthcare systems for the prescription of key anti-dementia drugs. Yet there was "clear evidence" that early diagnosis and intervention improved outcomes for patients and carers.

Edward Leigh, the committee's Tory chairman, said dementia was "one of the last great taboo subjects ... The task of looking after a sufferer falls in most cases on informal carers, usually family members. They play a vital role, but their burden is a heavy one."

Neil Hunt, chief executive of the Alzheimer's Society, said: "The government is only just beginning to wake up to the reality of dementia. If we live to 65, one in three of us will die with dementia."

Ivan Lewis, the health minister, said that bringing the condition "out of the shadows" was now one of the Department of Health's priorities and a national plan would be published in the autumn.